4种硅藻检验方法的比较研究

A comparative study on four methods for detecting diatom

目的比较硝酸乙醇法、酶消化法、“破机罐”法和Soluene-350法在检验硅藻中各自的优缺点,为法医实际办案提供理论依据。方法取家兔肝、肾和骨髓3种组织各2g,分别用上述4种方法消化,比较4种不同方法分别将组织这些完全消化所需要的时间、消化能力、对硅藻的检出率以及对硅藻的破坏程度。结果消化时间以Solu-ene-350法耗时最长,其次是酶消化法,硝酸乙醇法和破机罐法耗时最短。4种方法消化能力的强弱依次是“破机罐”法、硝酸乙醇法、酶消化法、Soluene-350法。对梅尼小环藻(淡水)和桥弯藻(淡水),酶消化法的检出率最高,硝酸乙醇法其次,“破机罐”法和Soluene-350法最低。对舟形藻(海水),酶消化法的检出率高,其余3种方法几乎没检测到。扫描电镜观察:酶消化法对硅藻结构几乎没有破坏。其余3种方法对硅藻均有不同程度的破坏。结论从降低成本、提高检测效率角度,应选择“破机罐”法和硝酸乙醇法;从安全性和环保角度,或可疑水样为海水及硅藻密度较小时,应选择酶消化法;Soluene-350法因耗时长、成本高且硅藻检出率低,不适于在基层法医中推广。

Objective To compare the advantages and disadvantages of four methods（ nitric acid added ethanol ,enzymatic digestion ,disorganization can and Soluene- 350）for detecting diatom in order to provide theoretic basis for selection in medico - legal practice. Methods Three kinds of rabbit tissue of liver, kidney and bone marrow （each 2g in weight） were cut and minced respectively, and then each of them was completely digested by these four methods separately. Time for complete digestion , digestive capability, reclaiming ratio of diatom in these tissues and their destruction to diatom were comparatively analyzed. Results The longest digestive time spent in digesting the 3 kinds of different tissues was Soluene -350 method, followed by enzymatic method and nitric acid added ethanol method, and disorganization can method was the shortest, Disorganization can had the strongest digestive capability, nitric acid added ethanol method and enzymatic digestion methods took the second and third place respectively, and Soluene - 350 method was the weakest. For diatoms of Cyclotella and Cybella, the highest reclaiming ratio was enzymatic digestion method ; then, nitric acid added ethanol method ; the lowest, zymatic disorganization can and Soluene -350 methods. Most diatoms of Navicula could be extracted by endigestion method, but only a few of the diatoms could be detected by other three methods. Under canning electronic microscopy （ SEM）, the structure of diatoms remained almost intact by enzymatic digestion method, but destroyed by the other three methods. Conclusion Nitric acid added ethanol method and disorganization can method are better than others in terms of saving money and time in practice. Enzymatic digestion method should be selected from the point of view of safety and environmental protection or under the condition of the drowning fluid being sea water or with less diatoms in the fluid . Soluene -350 method is not suitable for use in the laboratory of basic units as it is time - consuming, expensive and noneffective ratio of reclaiming diatom.